In this work, the application of stir bar sorptive extraction (SBSE), as a fast and conventional method, has been investigated for the simultaneous preconcentration and determination of trace amounts of Cd(II) and Cu(II) ions in natural samples. For this purpose, the surface of stir bar was functionalized by amine functionalized nanoporous silica and characterized by IR spectroscopy, X-ray powder diffraction (XRD), Atomic force microscopy (AFM) and N2 adsorption. In this approach, after the preconcentration of Cd(II) and Cu(II) ions and removing the matrix interferences using modified stir bar, the amounts of these ions were determined in eluent by flame atomic absorption spectroscopy (FAAS). Various parameters on adsorption and elution steps including pH of sample, adsorption kinetic, eluent parameters (type, volume and concentration) and elution time, have been optimized in this study. The limits of detection (LOD) were 1.6 and 13.8 ng mL-1 (recovery of 83.5 and 88.1%) for cadmium and copper ions, respectively. The preconcentration factors were 133 and 137 and the relative standard deviations (RSD) of the method were 5.7 and 4.6% for Cd(II) and Cu(II) ions, respectively. As the key point in this study seems to be stir bar nanoporous structure, the analytical performance of this stir bar was compared to non-porous ones. The accuracy of this novel method has been confirmed using some standard references materials. Finally the potential of this method was investigated by determination of Cd(II) and Cu(II) ions in some real samples with complicated matrixes.
Mohammad Karimi, Forouzan Aboufazeli, Hamid Reza Lotfi Zadeh Zhad, Omid Sadeghi and Ezzatollah Najafi
Mohammad Najafi, Abazar Roustazadeh, Ali Asghar Moshtaghie and Mohsen Ani
Exposure to hexavalent chromium compounds is associated with the risk of lung cancer, dermatitis, gastrointestinal ulcers, and other tissue damages. The aim of this study was to compare liver isoenzyme and total serum activities of aspartate aminotransferase (AST) as cytotoxic biomarkers of acute and chronic cytotoxicity of CrVI. We investigated the extent of cell damage caused by chromium(VI) in acute (2.5 mg kg-1) daily doses administered over five days and chronic (0.25 mg kg-1 and 0.5 mg kg-1) daily doses administered over 15 to 60 days by measuring total AST in serum and low molecular weight AST (LMW-AST) and high molecular weight AST (HMW-AST) activities in thirty liver fractions. We also evaluated the kinetic properties and electrophoretic mobility of the LMW- and HMW-AST isoenzymes in liver subcellular fractions. Liver LMW-AST and total serum AST activities significantly decreased after 15 days of exposure (P<0.05). With continued treatment, AST activity increased by 15.67 % (P<0.05). Interestingly, changes in serum AST activity were similar to changes in the liver LMW-AST isoenzyme. Our results confirmed that total serum AST activity may serve as a reliable tissue biomarker for long-term exposures to CrVI, but they also suggest that the LMW-AST isoenzyme could be even more sensitive.
Mohammad Najafi, Morteza Nouruzi Yeganeh, Arezoo Miraftabi, Reza Zarei and Isa Noormohammadi
Background Glaucoma is a highly prevalent eye disease related to optic nerve lesions and visual field defects. Primary Open-Angle Glaucoma (POAG) is a type of glaucoma that occurs frequently with unknown etiology. In this study, we investigated the serum levels of selenium, selenoprotein P1, glutathione, hemolysate glutathione peroxidase1 (GPx1) activity and aqueous humour selenium in POAG patients.
Methods Ninety sex- and age-matched subjects (POAG patients; n=45 and, controls; n=45) with the controlled confounders (smoking, hypertension and alcohol beverages) were recruited on clinical histories and exams. The serum and aqueous humour selenium levels were measured using GFAAS technique. The serum selenoprotein P1 level was assayed with the ELISA method. The hemolysate GPx1 activity and serum reduced glutathione level were also measured using known colorimetric techniques.
Results The serum selenium (P=0.01) and selenoprotein P1 (P<0.001) levels were significantly high in POAG patients. Furthermore, the aqueous humour selenium level was significantly high among patients as compared to controls (64.68±13.07 vs. 58.36±13.76 ng/mL, P=0.02). The results did not show a significant difference (P=0.36) in the hemolysate GPx1 activity between the groups. The cutoff points for intraocular pressure (IOP) and serum selenoprotein P1 parameters were estimated to be 39 mmHg (sensitivity 97.5%; 1-specificity 6.5%) and 188 mg/mL (sensitivity 93.5%; 1-specificity 14%), respectively.
Elham Softanmohammadi, Sadegh Piran, Asghar Mohammadi, Bita Hosseni, Faezeh Naseri, Mohammad Shabani and Mohammad Najafi
Background: Serum small dense LDL-cholesterol (sdLDL-C) value is suggested to be an important risk factor for atherosclerosis. Since sdLDL-C changes may be related to PCSK9 and SREBP-2 functions, the aim of this study was to investigate correlations between sdLDL-C, circulating PCSK9, SREBP-2 expression and some lipid parameters in serum and buffy coat fraction of healthy subjects.
Methods: One hundred and twenty-four subjects were randomly included in the study. The lipid profile was measured using routine laboratory methods. The serum sdLDL-C level was calculated by a heparin-related precipitation technique. The cellular LDL-C/protein and cholesterol/protein values were measured after lysing of cells with methanol/chloroform binary solvent. The circulating PCSK9 level was measured using ELISA technique. The SREBP-2 expression level was estimated using the RT-qPCR technique.
Results: Data showed significant correlations between LDL-C, TG and sdLDL-C levels (r=0.34, p=0.001; r=0.2, p=0.04). The circulating PCSK9 level was correlated to LDL-C (r=0.29, p=0.04), but not to sdLDL-C (r=−0.08, p=0.57). Also, cellular LDL-C value was not related to serum LDL-C level (r=−0.12, p=0.39). Furthermore, there was an inverse correlation between cellular LDL-C/protein value and estimated de novo cholesterol/protein value (r=−0.5, p=0.001). Similar results were observed for cellular LDL-C/protein value and SREBP-2 expression level (r=−0.52, p=0.004).
Conclusions: We concluded that the serum sdLDL-C value is not related to circulating PCSK9. Furthermore, SREBP-2 regulatory system was able to elevate the cellular cholesterol level after reducing LDL influx. We suggest to investigate the cellular sdLDL fate and lipid synthesis pathways in PCSK9-targeting studies.